Ruby Wraper to Gnuplot

plotter.rb

require 'open3'

class GNUPlotter < Struct.new(:data, :params)
  def plot
    image, s = Open3.capture2("gnuplot", stdin_data: gnuplot_commands, binmode: true)
    system "open #{params[:image_name]}"
  end

  private
  def gnuplot_commands
    commands = %{
      set terminal png font "/Library/Fonts/Arial.ttf" 14
      set title "#{params[:title]}"
      set xlabel "#{params[:x_axis_title]}"
      set ylabel "#{params[:y_axis_title]}"
      set output "#{params[:image_name]}"
      set key off
      plot "-" with points
    }

    data.each do |x, y|
      commands << "#{x} #{y}\n"
    end

    commands << "e\n"
  end
end

sound_data = File.read("guitar_first_string.dat").split("\n")[2..-1].map { |row| row.split.map(&:to_f) }.
  map { |r| r.first(2) }

plot_params = {
  image_name: "plot.png",
  title: "Guitar first string sound",
  x_axis_title: "Time, s",
  y_axis_title: ".wav signal"
}

plotter = GNUPlotter.new(sound_data, plot_params)
plotter.plot

Reference: http://makaroni4.com/ruby/hacking/2014/03/26/how-to-tune-guitar-with-ruby/